Tape unmounting protocol

Abstract

Described are techniques for a tape unmounting protocol. The techniques include selecting a tape for unmounting from a plurality of tape drives, where the tape for unmounting includes a remaining capacity below a first threshold and a number of migrated files below a second threshold. The techniques further include unmounting the tape for unmounting from a tape drive.

What is claimed is: 
     
       1. A computer-implemented method comprising:
 accepting a request for copying a file from an unmounted first tape to a primary storage, wherein the accepting comprises:
 determining that the first tape is not mounted on any tape drive; and 
 determining that each of a plurality of tape drives includes a mounted tape; 
 
 selecting a second tape for unmounting from the plurality of mounted tape drives, wherein the second tape includes a remaining capacity below a first threshold and a number of migrated files below a second threshold; 
 unmounting the second tape from a tape drive; 
 mounting the first tape on the tape drive; and 
 performing the request by copying the file from the first tape to the primary storage using the tape drive. 
 
     
     
       2. The method of  claim 1 , further comprising:
 storing a table including, for respective tapes, respective numbers of migrated files, respective numbers of premigrated files, and respective available capacities; and 
 wherein selecting the second tape for unmounting includes accessing the table to retrieve the remaining capacity and the number of migrated files for the second tape for unmounting. 
 
     
     
       3. The method of  claim 1 , wherein the second tape for unmounting including the remaining capacity below the first threshold further includes a least amount of remaining capacity relative to other tapes that are mounted on the plurality of tape drives. 
     
     
       4. The method of  claim 1 , wherein the second tape for unmounting including the number of migrated files below the second threshold further includes a least number of migrated files relative to other tapes that are mounted on the plurality of tape drives. 
     
     
       5. The method of  claim 1 , wherein the request is a recall request. 
     
     
       6. The method of  claim 1 , wherein the method is executed by a hierarchical storage management (HSM) system including the primary storage and a secondary storage comprising a tape storage system. 
     
     
       7. The method of  claim 6 , wherein the method is performed according to software that is downloaded to the HSM system from a remote data processing system, and wherein the method further comprises:
 metering a usage of the software; and 
 generating an invoice based on metering the usage. 
 
     
     
       8. A system comprising:
 one or more processors; and 
 one or more computer-readable storage media storing program instructions which, when executed by the one or more processors, are configured to cause the one or more processors to perform a method comprising: 
 accepting a request for copying a file from an unmounted first tape to a primary storage, wherein the accepting comprises:
 determining that the first tape is not mounted on any tape drive; and 
 determining that each of a plurality of tape drives includes a mounted tape; 
 
 selecting a second tape for unmounting from the plurality of mounted tape drives, wherein the second tape for unmounting includes a remaining capacity below a first threshold and a number of migrated files below a second threshold; 
 unmounting the second tape for unmounting from a tape drive; 
 mounting the first tape on the tape drive; and 
 performing the request by copying the file from the first tape to the primary storage using the tape drive. 
 
     
     
       9. The system of  claim 8 , wherein the one or more computer-readable storage media store additional program instructions configured to cause the one or more processors to perform the method further comprising:
 storing a table including, for respective tapes, respective numbers of migrated files, respective numbers of premigrated files, and respective available capacities; and 
 wherein selecting the second tape for unmounting includes accessing the table to retrieve the remaining capacity and the number of migrated files for the second tape for unmounting. 
 
     
     
       10. The system of  claim 8 , wherein the second tape for unmounting including the number of migrated files below the second threshold further includes a least number of migrated files relative to other tapes that are mounted on the plurality of tape drives. 
     
     
       11. The system of  claim 8 , wherein the request is a recall request. 
     
     
       12. The system of  claim 8 , wherein the one or more processors and the one or more computer-readable storage media are associated with a hierarchical storage management (HSM) system including the primary storage and a secondary storage comprising a tape storage system. 
     
     
       13. A computer-implemented method comprising:
 determining that a second tape is not mounted on any tape drive; 
 determining that there are no available tape drives of a plurality of tape drives; 
 selecting a tape for unmounting from a tape drive, wherein the tape includes a remaining capacity below a first threshold and a number of migrated files below a second threshold; 
 unmounting the tape from the tape drive; 
 mounting the second tape on the tape drive in response to unmounting the tape from the tape drive; and 
 copying a file from the second tape to a primary storage using the tape drive. 
 
     
     
       14. The method of  claim 13 , wherein the method further comprises:
 storing a table including, for respective tapes, respective numbers of migrated files, respective numbers of premigrated files, and respective available capacities; and 
 wherein selecting the tape for unmounting includes accessing the table to retrieve the remaining capacity and the number of migrated files for the tape for unmounting. 
 
     
     
       15. The method of  claim 13 , wherein the tape for unmounting including the remaining capacity below the first threshold further includes a least amount of remaining capacity relative to other tapes that are mounted on the plurality of tape drives. 
     
     
       16. The method of  claim 13 , wherein the tape for unmounting including the number of migrated files below the second threshold further includes a least number of migrated files relative to other tapes on the plurality of tape drives. 
     
     
       17. The method of  claim 13 , wherein the copying the file is performed in response to a recall request. 
     
     
       18. The method of  claim 13 , wherein the method is executed by a hierarchical storage management (HSM) system including the primary storage and a secondary storage comprising a tape storage system.